A “scenic open-air bath” is a powerful motivator when guests choose a place to stay, yet its quality is hard to see from room categories or price lists alone. In this report, we use natural language processing to analyze guest reviews actually posted by travelers, aggregating mentions related to experiential quality—open-air baths (rotenburo), views, free-flowing hot-spring water (gensen kakenagashi), and water quality (sensitsu)—at the regional level. Rather than price or ADR, we use a qualitative axis based on reviews to surface both the top-rated regions for scenic open-air baths and, conversely, the areas where this experience is rare.

Measuring the Density of “Scenic Open-Air Bath” Experiences in Reviews

The starting point of this analysis is positive review mentions tying together “open-air bath” and “view.” A standard star score averages over many factors—cleanliness, service, food—so it is hard to tell whether the scenic rotenburo is truly the property’s centerpiece. We therefore calculated, for each region, the share of reviews containing positive mentions of the open-air bath (the open-air bath mention rate). The higher this value, the more strongly that area’s properties position the open-air bath and surrounding scenery at the heart of the guest experience, and the more vividly guests remember it.

Nationwide, positive open-air bath mentions were most concentrated in Shizuoka Prefecture, where target properties averaged a 25.3% mention rate. That works out to roughly one in four reviews discussing the open-air bath or the view. The coastal hot-spring areas of Izu and Atami clearly stand out for the strength of their ocean-view rotenburo experience. They are followed by Niigata (21.5%), Fukushima (20.5%), Gifu (19.8%), and Gunma (18.9%)—a lineup of inland mountain hot-spring areas. The gap between a hot-spring area’s brand recognition and actual guest satisfaction is something we have also examined using 955,000 reviews, as analyzed in our study on the disconnect between popular hot-spring rankings and real guest satisfaction.

Source: HotelBank Editorial Team analysis (NLP; average open-air bath mention rate across target properties per region).

One striking point is that famously branded hot-spring prefectures such as Oita and Wakayama (Shirahama) do not dominate the top of the list. Instead, the high mention rates went to areas where “you can talk about the bath and the scenery in the same breath”—Shizuoka with the Izu Peninsula, Niigata and Fukushima as the homeland of snow-viewing baths, and Gifu with Okuhida and Gero. Rather than the raw number of open-air baths, what differentiates these regions appears to be the strength of the impression left by an open-air bath that is fully integrated with its scenery.

“Breadth” and “Intensity” in Top Regions

The strength of scenic open-air baths has two axes. The first is breadth—how widely properties with dense mentions are distributed. The second is intensity—how high the per-property mention rate runs. Sorting regions along these two axes reveals each area’s character.

Shizuoka is top-tier on both axes: the number of properties with mention rates above 20% hits the analysis cap of 100, and the average mention rate of 25.3% is also the highest in the country. It is the overall leader in scenic open-air baths, combining supply depth with experiential intensity. By contrast, Tochigi, Nagano, and Hokkaido also reach 100 target properties—but their average mention rates land in the 12–16% range. These are broader markets where properties of many different price points and types coexist (business, sightseeing, ski, etc.), so “open-air-bath-led” and “open-air-bath-as-side-attraction” properties live alongside each other.

Conversely, Niigata (68 properties, 21.5%) and Fukushima (49 properties, 20.5%) cannot match Shizuoka on supply, but their per-property intensity stands out. A clear theme—snow-viewing rotenburo—has imprinted itself strongly on guests’ impressions in these areas.

Source: HotelBank Editorial Team analysis (NLP). X-axis = number of target properties (top-mention properties, capped at 100); Y-axis = average open-air bath mention rate.

Regions Where Scenic Open-Air Baths Are Rare

The flip side is equally clear: there are areas where the scenic open-air bath experience is comparatively rare. Tokyo (6.6% open-air bath mention rate), Osaka (7.6%), Okinawa (8.3%), and Kyoto (10.3%) all see heavy lodging demand, yet their reviews contain few positive mentions of open-air baths or views. Urban markets are dominated by business and sightseeing-access stays, and the supply of properties with an open-air bath is limited to begin with.

Read the other way, this means that properties in these regions that can offer a scenic open-air bath gain a powerful differentiator in reviews. On Tokyo’s bayfront, for example, high-floor ocean-view large bathhouses collect comments such as “open until 6 a.m.” and “the view from the 15th floor is the best,” confirming that the view-plus-water combination is rewarded even in urban formats. In Okinawa the mention rate itself is low, but support for sea-facing hot-spring baths runs deep—an area where additional supply would unlock substantial upside.

Source: HotelBank Editorial Team analysis (NLP). Lower open-air bath mention rate = scenic rotenburo experiences are comparatively rare.

Kyoto sits closer to the rare end at 10.3%, yet its May 2026 ADR of ¥47,300 (+24.7% YoY) makes it one of the highest-priced markets nationwide. Kyoto is a market valued on a different set of axes—machiya townhouses, gardens, location—and is differentiated by something other than the scenic open-air bath. The meaning of “rarity” differs by region, a nuance worth keeping in mind.

Water Quality and Free-Flowing Hot Springs: Another Qualitative Axis

Alongside the scenic open-air bath, two further qualitative axes drive review conversations about hot springs: water quality (sensitsu) and free-flowing hot-spring water (gensen kakenagashi). Among properties with the densest positive mentions of water quality are Gero Onsen Suimeikan (Gifu Prefecture, 293 of 1,796 target reviews = 16.3% mention water quality) and Ureshino Onsen Hotel Kasuien (Saga Prefecture, 190 of 802 = 23.7%). Phrases like “egg-skin baby-smooth water” and “beauty-skin hot spring” have become an integral part of the brands themselves.

As for free-flowing hot-spring water, smaller properties tend to post higher mention rates. Muso-an Biwa in Toi Onsen on the Nishi-Izu coast (Shizuoka) sees 11.1% of its 307 reviews mention gensen kakenagashi—evidence that, in reviews as in marketing, the strategy of small properties showcasing water freshness through limited room counts is clearly winning support. The “visual” axis of scenic views and the “tactile” axis of water quality and free-flowing water represent different directions a property can stake out for its hot-spring value. Properties that can combine both have meaningful growth headroom.

Source: HotelBank Editorial Team analysis (NLP). Properties with the highest water-quality positive-mention rates (past 24 months).

ADR and Experience Value in Top-Rated Regions

Top-rated scenic-open-air-bath regions are not necessarily ultra-premium. Looking at area-average ADR (all plans) in May 2026, Shizuoka—the mention-rate leader—runs about ¥36,000, Gunma about ¥33,700, Gifu about ¥30,000, and Nagano about ¥30,700. In contrast, Fukushima (around ¥25,700), Tochigi (around ¥27,700), and Niigata (around ¥27,100) combine high open-air bath mention rates with comparatively restrained ADRs. In other words, there are regions where, relative to the experience value of a scenic open-air bath, prices remain at moderate levels. For demand-side trends—how spending flows toward premium hot-spring ryokans—see our analysis of the 2026 summer bonus and premium hot-spring ryokan ADR.

These regions can be read as “strongly supported on scenery and water quality, yet still moderately priced”—areas where a sense of value remains for guests. From the operator’s side, areas with clear evidence of experience value (high open-air bath mention rates in reviews) likely retain room to broaden revenue through staged pricing and a richer upper-tier plan mix. Translating the qualitative strength of a scenic open-air bath into pricing strategy is set to become a defining theme.

Source: HotelBank Editorial Team analysis (NLP) + MetroEngines Research (ADR, May 2026).

Conclusion

Viewing scenic open-air baths through the qualitative lens of guest reviews surfaces regional character that price lists alone cannot capture. Shizuoka is the overall leader, combining supply breadth and experiential intensity. Niigata, Fukushima, Gifu, and Gunma stand out for the per-property density of mentions tied to snow-viewing and mountain rotenburo. Conversely, Tokyo, Osaka, Kyoto, and Okinawa see the scenic open-air bath experience only rarely—signaling a differentiation opportunity for urban properties that can pair a view with hot-spring water.

Layering on the “tactile” axes of water quality and free-flowing hot-spring water, the directions a property can stake out for hot-spring value become multi-dimensional. Scenery (sight), water quality (touch), and free-flowing water (freshness)—visualizing all three through review data lets each region’s and each property’s strengths and headroom emerge in three dimensions. Top-rated regions where ADR has yet to fully catch up retain real room to connect experience value to price.